In the related art, there is a known hybrid turbocharger which not only utilizes engine exhaust gas discharged from an internal-combustion engine as a compressor driving force of the turbocharger but also utilizes the same as power for driving a generator motor, so as to obtain generating power. FIG. 10 illustrates a configuration of the hybrid turbocharger in the related art. As illustrated in FIG. 10, for example, a hybrid turbocharger 100 includes an exhaust turbine 101 that is driven by exhaust gas discharged from an internal-combustion engine such as a diesel engine for a marine vessel, a compressor 102 that is driven by the exhaust turbine 101 and boosts outside air to the internal-combustion engine, and a generator motor 103 that is joined to rotary shafts of the exhaust turbine 101 and the compressor 102. The generating power of an alternating-current obtained by the generator motor 103 is converted into direct-current power by a converter 104. Thereafter, an inverter 105 inverts the direct-current power into three-phase alternating-current power having a frequency corresponding to that of a system 106, thereby being supplied to the system 106. A smoothing capacitor 107 for absorbing a fluctuation of a direct-current voltage is provided between the converter 104 and the inverter 105 while being connected thereto.
Generally, in the hybrid turbocharger, a motoring operation (an operation state in which electric power is supplied from an inverter to a generator motor) and a regenerating operation of the generator motor are alternately determined by an upstream controller which controls the internal-combustion engine. Therefore, the regenerating operation is prohibited when the motoring operation is selected by the upstream controller. On the contrary, the motoring operation is prohibited when the regenerating operation is selected.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-214143
Patent Document 2: Japanese Unexamined Patent Application Publication No. 7-95775